/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/
package com.tyijian.springside.core.persistence;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

import org.apache.commons.lang3.StringUtils;
import org.springframework.data.jpa.domain.Specification;

import com.google.common.collect.Lists;
import com.tyijian.springside.core.utils.Collections3;

/**
 * 动态多条件查询组合
 * 
 * @author yangjp
 *
 */
public class DynamicSpecifications {

	public static <T> Specification<T> bySearchFilter(final Collection<SearchFilter> filters,
			final Class<T> entityClazz) {
		return new Specification<T>() {
			@SuppressWarnings({ "unchecked", "rawtypes" })
			@Override
			public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
				if (Collections3.isNotEmpty(filters)) {

					List<Predicate> predicates = Lists.newArrayList();
					for (SearchFilter filter : filters) {
						// nested path translate, 如Task的名为"user.name"的filedName,
						// 转换为Task.user.name属性
						String[] names = StringUtils.split(filter.fieldName, ".");
						Path expression = root.get(names[0]);
						for (int i = 1; i < names.length; i++) {
							expression = expression.get(names[i]);
						}

						try {
							// logic operator
							SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
							switch (filter.operator) {
							case EQ:
								predicates.add(builder.equal(expression, filter.value));
								break;
							case LIKE:
								predicates.add(builder.like(expression, "%" + filter.value + "%"));
								break;
							case GT:
								predicates.add(builder.greaterThan(expression, (Comparable) filter.value));
								break;
							case LT:
								predicates.add(builder.lessThan(expression, (Comparable) filter.value));
								break;
							case GTE:
								predicates.add(builder.greaterThanOrEqualTo(expression, (Comparable) filter.value));
								break;
							case LTE:
								predicates.add(builder.lessThanOrEqualTo(expression, (Comparable) filter.value));
								break;
							case TGT:
								predicates.add(builder.greaterThan(expression, (Comparable) sdf.parse((String) filter.value)));
								break;
							case TLT:
								predicates.add(builder.lessThan(expression, (Comparable) sdf.parse((String) filter.value)));
								break;
							case TGTE:
								predicates.add(builder.greaterThanOrEqualTo(expression, (Comparable) sdf.parse((String) filter.value)));
								break;
							case TLTE:
								predicates.add(builder.lessThanOrEqualTo(expression, (Comparable) sdf.parse((String) filter.value)));
								break;
							}
						} catch (ParseException e) {
							e.printStackTrace();
						}
					}

					// 将所有条件用 and 联合起来
					if (!predicates.isEmpty()) {
						return builder.and(predicates.toArray(new Predicate[predicates.size()]));
					}
				}

				return builder.conjunction();
			}
		};
	}
}
